Watchdog Circuitry - Matrox Helios Series Installation And Hardware Reference

94 Chapter 4: Matrox Helios hardware reference
Under optimum conditions, Matrox Helios can exchange data with the Host at a
peak transfer rate of 1 Gbyte/sec. For Matrox Helios eCL, eA, and eD, these
conditions include using the board in a x4 or x8 PCIe slot with at least 4 active
lanes. For Matrox Helios XCL, XA, and XD, these conditions include using the
board in a 133 MHz PCI-X slot. Matrox Helios XCL, XA, and XD can also be
used with a conventional 3.3 or 5 V
transfer rate is reduced (132 Mbytes/sec for a 33 MHz 32-bit PCI slot,
266 Mbytes/sec for a 66 MHz 32-bit PCI slot, and 532 Mbytes/sec for a 66 MHz
64-bit PCI slot).
Using the PCIe/PCI/PCI-X bus, Matrox Helios can also access Host DMA
memory (physically contiguous, non-paged memory). An advantage of DMA
memory is that a bus mastering device (such as Matrox Helios) can access this
memory without the help of the Host CPU.
As previously mentioned, you can also map some Matrox Helios main memory
onto the PCI bus so that you can use a Host pointer to access this memory, or you
can access it directly from another PCIe/PCI/PCI-X bus master.

Watchdog circuitry

Matrox Helios eCL/XCL, eA/XA, and eD/XD all have Watchdog circuitry
automatically recover from application or system failure. The Watchdog circuitry
automatically reboots your computer when, for some reason, your computer hangs
for longer than a pre-set amount of time.
The Watchdog circuitry works based on an integrated timer. When the Watchdog
circuitry is enabled, it must receive a reset signal ("pulse") from an application or
from the Matrox Helios driver within the time specified by the timer. Every time
the signal is received, Watchdog resets its timer. If, however, the Watchdog
circuitry does not receive a signal for a period longer than the time allotted by the
timer, it will send a hardware reset signal to reboot the computer.
1. 5 V starting from revision 1 of the Matrox Helios PCB; revision 0 is only 3.3 V PCI
tolerant.
2. Starting from revision 1 of the Matrox Helios XCL PCB; whereas, present on the
Matrox Helios XA PCB as of revision 0.
1
PCI slot, in which case the maximum
2
to